Reactivity and analytical performance of oxygen as cell gas in inductively coupled plasma tandem mass spectrometry

The reactivity and analytical performance of O-2 as cell gas in inductively coupled plasma tandem mass spectrometry was investigated. Selected analytes in a wide-mass range were divided in three groups according to their reactivity: G1 represents elements with high oxygen affinity (Ce, La, P, Sc, Ti, and Y), G2 contains elements that may partially react with oxygen (As, Ba, Mo, Si, Sr, and V), and G3 comprises elements expected to be less reactive towards oxygen (Al, Bi, Cu, Mg, Pb, and Pd). On-mass and mass-shift modes were evaluated by monitoring atomic and metal oxide ions, respectively. Analytical signal profiles, oxide percentages, sensitivities and limits of detection for oxygen flow rates varying from 0.1 to 1.0 mL min(-1) were also studied. Group 1 elements plus As and V presented better sensitivities and LODs when measuring oxides, which were the major species for all flow rates evaluated. Molybdenum and Si oxides presented intermediate behavior and MoO fraction was up to 47% and limit of detection was the same as that obtained in on-mass mode. For others G2 and G3 elements, on-mass mode presented higher sensitivity and better LODs, with estimated oxide contents lower than 10%. In most cases, increasing oxygen flow rates led to lower sensitivities and worse LODs. (C) 2016 Elsevier B.V. All rights reserved.